The objective of this Core Unit is to provide a cental mechanism to assist investigators with the design and execution of hematopoietic stem cell transduction studies in the baboon. The Core Unit will provide three main functions. 1) The design and the planning of the baboon experiments. The Unit will ensure that baboons will be available and adequately prepared for the individual studies. 2) The marrow harvest and the reinfusion of transduced cells. Marrow will be harvested from femura and humeri and given to Core Unit B for CD34 separations and then to the individual investigators for transduction. Before reinfusion of transduced cells the animals will receive a myeloablative dose of total body irradiation. All animals will receive an intravenous catheter that is connected via a tether system to the outside of the cage. This facilitates the daily administration of fluids and broad-spectrum antibiotics and will also be used for reinfusion of transduced baboon CD34 cells. 3) The post-transplant monitoring and care of the animals and obtaining the blood samples and bone marrow samples required for the studies. All animals will be examine daily by the Core Unit directors and health status and treatment plan will be discussed with specially trained personnel at the Primate Center. The directors of this ore Unit have extensive experience in conducting stem cell transplantation studies in the baboon. The Primate Center at the University of Washington has set aside a special room for our baboon studies to accommodate the intensive care required for these studies and the staff at the Primate Center is specially trained to work with baboons involved in stem cell transplantation studies. In many ways, the operation of this baboon stem cell unit is modeled after a human stem cell transplantation unit to assure the high quality care required for these studies.